Turbomachine rotor assembly



6, 1966 D. J. HARLOW 3,266,770

TURBOMACHINE ROTOR ASSEMBLY Filed Dec. 22, 1961 3 was .1 i l i n/Ivan/E)- 3,266,770 [C6 Patented August 16, 1966 3,266,770 TURBOMACHINEROTOR ASSEMBLY Doris Jean Harlow, Cincinnati, Ohio, assignor to GeneralElectric Company, a corporation of New York Filed Dec. 22, 1961, Ser.No. 161,736 3 Claims. (Cl. 2.5339.15)

This invention relates to a turbomachine rotor assembly and moreparticularly to a lightweight assembly with provision for air coolingand blade damping.

In turbomachinery, and primarily in axial flow gas turbineslfor use inaircraft, it is well known to manufacture the rotor wheel and bladesseparately and provide means for mounting the blades about the peripheryof the wheel. However, it is necessary in such an assembly to providemeans for sealing against the axial flow of gas between the adjacentblade shanks or that portion of the blade which does not extend directlyinto the gas flow passageway. This is necessary to prevent leakage of aportion of the primary gas flow around the passageway through which thevane portion of the blades extend; said leakage would thereby reduce theefficiency of the rotor assembly. One manner of doing this in the pasthas been to form integral with the blade shanks peripheral extendingflanges which when all the blades are assembled about the rotor wheel,serve to prevent this axial gas flow past the shank portions of theblade. However, such an assembly serves to decrease the flexibility ofthe blade shanks and thereby introduces additional vibrational problemsnot present with the use of flexible blade shanks.

Also, where the rotor assembly is subjected to high temperature gas flowas is the case with a turbine assembly, it is necessary to provide forcooling fluid circulation through the rotor assembly to cool the blades.Similarly such assemblies have served to stiffen the blade shanks wherethe structure is formed integral with the blade as described heretofore,or has at times consisted of providing fluid passageways internal to theblade shanks which greatly increased the manufacturing problems and alsoserved to weaken the blade shanks.

A verybeneficial assembly would "be one which provides'for the mountingof blades about the periphery of theroto'r Wheel and seals against axialgas flow past the blade shanks iwhile not limiting the flexibility ofthe blades in any manner. Additionally, the assembly should be one whichprovides for fluid cooling of the blade assembly with a minimum ofinternally formed passages in the rotor wheel and blades and, ifpossible, rather than merely not introducing any new vibrationalproblems within the assembly, would additionally provide means fordamping what vibrations might exist between the blades utilized. Allthese functions preferably should be performed by the simplest and mosteasily manufactured and assembled rotor assembly.

It is accordingly one object of this invention to provide a lightweightturbomachine rotor assembly.

It is another object of this invention to provide a lightweightturbomachine rotor with an integrated assembly providing means fordamping vibration within the blade assembly, and if necessary, means forcooling the rotor blades.

According to one embodiment of the invention there is provided aturbomachine rotor assembly comprising a rotor wheel having a pluralityof blades circumferentially spaced about the periphery and extending ina radial direction. These blades include a shank, vane portion and aplatform therebetween, with the vane portion having internal coolingpassages opening to the outside of the blade and connecting with a fluidpassage leading from the exterior of the blade shank. Flat baflle platesextending from the rotor wheel to the blade platform are located on eachside of these blade shanks to prevent axial flow of gas past the bladeshanks and to form with the blade shanks a cooling fluid passageway. Onebaflle is spaced from the rotor wheel in a manner to allow cooling fluidfrom the exterior to flow between the rotor wheel and the baffle intothe chamber formed by the bafiies and blade shanks and subsequently intothe internal cooling passages in the blade vane portion. The baffles areconnected at the edge adjacent the blade platforms by loosely attacheddamper pins extending axially between the blade shanks; said pins areforced by centrifugal force against the joints between adjacent bladeplatforms to seal the joints and, additionally, to damp vibrationsbetween the adjacent blades. Other bolt fasteners may be inserted at thedovetail bases of the blades to both hold the battle plates in positionadjacent the rotor wheel and hold the blades in axial position on therotor wheel.

The invention will be further understood and its various objectives,features and advantages more fully appreciated by reference to theappended claims and the following detailed description when read inconjunction with the accompanying drawing, wherein:

In the drawing:

FIG. 1 is a partially exploded perspective view showing the entire rotorassembly,

FIG. 2 is a side plan view partially in section of the rotor assembly,

FIG. 3 is a top plan view of the rotor wheel with the baflle members inphantom,

FIG. 4 is a side plan view of the shank and dovetail portion of a rotorblade, and

FIG. 5 is an enlarged perspective view of the damper pin.

Referring now primarily to FIGS. 1 and 2, therein is illustrated a rotorwheel 11 having dovetail slots 12 circumferentially spaced about theperiphery. These slots are of the usual Christmas-tree shape which arewell known and widely used for positioning and attaching rotor bladesradially around the rotor wheel periphery. Extending radially from therotor wheel and attached to the rotor wheel at the dovetail slot arerotor blades 13 which include a base portion 14, shank portion 15, aplatform 16 and a vane portion 17. The base portion 14 of a blade formsone half of the cooperating structure to conform to the dovetail opening12 in the rotor wheel and the blades are positioned in pairs orSiamese-twin manner about the rotor. This method of attaching the bladeis more fully described in US. Patent 2,990,156, Marshall, et al. andprovides the advantages of allowing centrifugal force to impart a momenton the blades that are paired to force them together and damp vibrationstherebetween while simplifying the overall attachment of the blades.

The blades include internal air passages (not shown) in the vaneportions 17 which connect with cooling fluid passages passing throughthe platform 16 and open external of the blade shanks at openings 20. Asdenoted by the arrows in FIG. 2, cooling fluid may enter the openings 20and flowoutward through the shank and platform portions of the blades tosubsequently flow through the vane inter nal passages and be expelled inany convenient manner as by openings 21 at the extreme outer end of thevane.

As in normal turbomachines, only the vane portion 17 of the bladesextends into the primary gas flow of the turbomachine and duct wallsextend closely adjacent to the platform of the blade to contain thisprimary gas flow. Such duct walls are illustrated in part by the wallportions 23 and 24 of FIG. 2 with a similar wall (not shown) at theouter extremity of the blade forming the primary gas flow passageway. Itis necessary however to seal between adjacent blade shanks in the areabetween the platform and the rotor wheel to prevent gas passage past thejoint between the wall portion 23 and the platform 16 and then betweenthe blade shanks and lower the efliciency of the machine as well asallowing hot gases to cause corrosion, etc., of the rotor assembly. Toseal this shank area, bafiie plates and 26 are fastened in some suitablemanner as by bolting on the upstream and downstream sides of the bladeshanks as illustrated to prevent such gas leakage. These baflle platesinclude indented portions 27 and a grooved portion 28 which serves tostiffen the baffle walls and allows for thermal expansion in a radialdirection to prevent the introduction of high thermal stresses. Thebaffles are fastened to the rotor wheel edge by bolt fasteners 3bpassing through openings 31 in the baflles and openings 32 in the rotorwheel with baffle 25 abutting projections 33 on the rotor wheel 11 whichserve to space the inward edge of the baille from the wheel as will beexplained hereinafter.

Turning now to FIG. 4 briefly, there is illustrated a side view of theshank and base portion of a blade with the base portion including aprojection 34 extending in an axial direction normal to the blade axis.This projection as illustrated in FIG. 2 is such that when the bolt isinserted and a nut is attached the baflie 26 is drawn tightly againstthe rotor wheel and the baffle 25 is drawn against the ends of theprojection 33 on the rotor wheel and these projections 34 therebyallowing a space 35 between the baffle and wheel, the purpose of whichwill be further discussed hereinafter. Also a rotating seal member 36may be attached by this bolt 30 which extends in an axial direction andforms a labyrinth seal with a stationary seal member 37 for the purposeof sealing against air passage from the rotor axis area out toward therotor periphery.

The outer edges of the baflie plates 25 and 26 include elongatedopenings 40 which are located in the same radially extending plane asthe joint between adjacent pairs of blade platforms and spaced radiallyinward therefrom. A damper pin 41 which is better illustrated in FIG. 5is inserted so as to extend between baffle plates and hold the platesagainst axial deflection. This damper pin 41 consists of a halfcylindrical mid portion 42, a shoulder 43 which is slightly smaller thanthe openings 40 in the baflie plates and a screw threaded projection 44at each end. When the damper pins are inserted to extend axially betweenthe baflie plates, the rounded portion 42 fits adjacent the jointbetween adjacent blade platforms 16 with the shoulders 43 extendingthrough the openings 49 in the baffle plates. When a nut is tightened oneach end of the damper pin, it tightens against the shoulder 43 so as toallow a loose fit between the damper pin and the bafile plates whilestill providing axial support to these balfle plates.

By allowing a loose fit between thedamper pin and baflie plates, duringoperation the damper pin is forced radially outward by centrifugal forceand presses tightly against the adjacent blade platforms thereby tightlysealing the joint between these platforms to prevent gas leakage. Inaddition, this close rubbing contact between adjacent blade platformsserves to damp vibration or relative movement of these platforms andthereby serves to provide a more integrated overall blade assembly.

In addition, a rotating seal member 46 may be bolted by bolt 47extending through the rotor wheel which cooperates with a stationarymember 48 to form with the rotating seal member 36 a chamber 50 withinthe rotor assembly. When cooling air is introduced into this chamber, itmay be of sufficient pressure to cause its flow into the opening 35 orit may be radially accelerated by the rotating rotor assembly so as tobe centrifuged outward along the rotor wheel 11 and thereafter enter theopening 35 formed between the baffle 25 and the rotor wheel. As denotedby the arrows, this cooling air may then flow between the rotor wheeland baffle into a fluid passageway formed by the blade shanks 15 and thebaflle plates 25 and 26 along with the blade platforms 16 tosubsequently enter the openings 20 in the blades opening into thatpassageway and flow thereafter into the inner cooling passageways of thevanes 17 to cool the vanes when they are subjected to high temperaturegases of the primary gas flow, this flow being aided by the centrifugingaction of the rotating assembly.

It can be seen that by this assembly a lightweight rotor construction isafforded because of the unique use of complementing lightweight partswhich serve multiple functions in providing an integrated blade assemblywith cooling fluid passageways. In addition, this assembly is easilymanufactured and assembled with a minimum of readily interchangeable andreplaceable parts to facilitate maintenance. Also, by the use of theunique bafiie and rotor wheel cooling fluid passage, no small passagesthrough the rotor wheel are utilized which might clog or otherwiseincrease the cost of the assembly. Furthermore, by the use of bafiieplates of the type described heretofore, the aerodynamic losses of therotor assembly are decreased and the blade shanks are flexible therebydecreasing any vibration which might be caused by otherwise stiffshanks.

Certain preferred embodiments of the invention have been described andillustrated by way of example in the foregoing, but many modificationswill occur to those skilled in the art and it therefore should beunderstood that the appended claims are intended to cover all suchmodifications as follow in the true spirit and scope of the invention.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. A rotor assembly for an axial flow tunbomachine, comprising a rotorwheel,

a plurality of blades having shank and vane portions with a platformtherebetween,

said blades positioned to extend radially from said rotor wheel with theshank portions attached to said wheel and adjacent platforms abutting,

first and second bafile plates positioned on the upstream and downstreamsides of said blade shanks respectively to prevent the axial flow of gasbetween said shanks,

said bafiie plates including radially extending slots adjacent wheresaid platforms abut, damper pins supported from said slots andconnecting said plates in a manner to allow limited radial move ment ofsaid pins and hold said plates in position,

said damper pins positioned to rub against the joint formed by adjacentblade platforms to seal said joint and damp vibrations between adjacentblades,

said blades having internal cooling fluid passages opening into chambersformed by the blade shanks and baffle plates,

and means to introduce cooling fluid into these chambers for circulationthrough said blades.

2. A rotor assembly for an axial flow turbomachine, comprising a rotorwheel,

a plurality of blades having shank and vane portions with a platformtherebetween,

said blades positioned to extend radially from said rotor wheel with theshank portions attached to said wheel and adjacent platforms abutting,

first and second bafile plates positioned on the upstream and downstreamsides of said blade shanks respectively to prevent the axial flow of gasbetween said shanks,

said bafiie plates having radially extending openings adjacent wheresaid platforms abut,

said first baffle plate being axially spaced from said rotor wheel,

damper pins supported in said openings and connecting said plates, in amanner to allow limited radia-l movement of said pins and also hold saidplates in position,

said damper pins positioned to rub against the joint formed by adjacentblade platforms to seal said joint and damp vibrations between adjacentblades,

said blades having internal cooling fluid passages opening into chambersformed by the blade shanks and bafile plates,

and means to introduce cooling fluid to flow between said first baflleplate and said rotor wheel for circulation through said blade internalcooling fluid passages to cool said blades.

3. A rotor wheel assembly for an axial flow turbornachine, comprising arotor Wheel,

a plurality of blades having shank and vane portions with a platformtherebetween,

said blades positioned to extend radially from said rotor Wheel with theshank portions attached to said wheel and adjacent platforms abutting,

a first baflie plate positioned to extend radially from said platformsto said wheel to prevent flow of gas between said blade shanks from anaxial direction,

said rotor wheel having projections on the radial surface to axiallyspace the inner edge of said first baffle plate,

a second baffle plate positioned to extend radial-1y from said platformto said Wheel on the other side of said blade shanks,

said first and second bafile plates including radially slotted portions,

damper pins supported from said slotted portions and connecting saidfirst and second baflle plates to hold these plates in position,

said damper pins connecting said plates in a manner to allow some radialmovement of said pins with respect to said plates,

said damper pins positioned against the joint formed by adjacent bladeplatform to seal said joint and damp vibration between adjacentplatforms,

said blades having internal cooling fluid passages opening external tothe blades at said blade shanks,

and means to introduce cooling fluid to flow between said first baffleplate and said rotor wheel for circulation through said blade internalcooling fluid passages.

References Qited by the Examiner UNITED STATES PATENTS EDGAR W.GEOGHEGAN, Primary Examiner.

SAMUEL FEINBERG, BENJAMIN A. BORCHELT,

Examiners.

S. W. ENG-LE, Assistant Examiner.

1. A ROTOR ASSEMBLY FOR AN AXIAL FLOW TURBOMACHINE, COMPRISING A ROTORWHEEL, A PLURALITY OF BLADES HAVING SHANK AND VANE PORTIONS WITH APLATFORM THEREBETWEEN, SAID BLADES POSITIONED TO EXTEND RADIALLY FROMSAID ROTOR WHEEL WITH THE SHANK PORTIONS ATTACHED TO SAID WHEEL ANDADJACENT PLATFORMS, ABUTTING, FIRST AND SECOND BAFFLE PLATES POSITIONEDON THE UPSTREAM AND DOWNSTREAM SIDES OF SAID BLADE SHANKS RESPECTIVELYTO PREVENT THE AXIAL FLOW OF GAS BETWEEN SAID SHANKS, SAID BAFFLE PLATESINCLUDING RADIALLY EXTENDING SLOTS ADJACENT WHERE SAID PLATFORMS ABUT,DAMPER PINS SUPPORTED FROM SAID SLOTS AND CONNECTING SAID PLATES IN AMANNER TO ALLOW LIMITED RADIAL MOVEMENT OF SAID PINS AND HOLD SAIDPLATES IN POSITION, SAID DAMPER PINS POSITIONED TO RUB AGAINST THE JOINTFORMED BY ADJACENT BLADE PLATFORMS TO SEAL SAID JOINT SAID BLADES HAVINGINTERNAL COOLING FLUID PASSAGES OPENING INTO CHAMBERS FORMED BY THEBLADES SHANKS AND BAFFLE PLATES, AND MEANS TO INTRODUCE COOLING FLUIDINTO THESE CHAMBERS FOR CIRCULATION THROUGH SAID BLADES.